In transportation vehicle systems such as overhead traveling vehicle systems, inter-bay routes are provided as long distance transportation routes and intra-bay routes are provided along a plurality of processing equipment. In general, the intra-bay route is a circular route. Vehicles are accessible to the inter-bay route at one or more positions. According to the disclosure of Japanese Laid-Open Patent Publication No. 2006-313767, the minimum number of transportation vehicles for each intra-bay route is determined, and if shortage of the vehicles occurs, additional vehicles are brought from other intra-bay routes, and no transportation to the outside of the bay is performed until arrival of the additional transportation vehicles. However, if the minimum number of transportation vehicles is determined for each bay, a large number of transportation vehicles are required. For example, if at least one transportation vehicle is allocated in each bay, the total number of the transportation vehicles needs to be at least the number of bays. If the minimum number of transportation vehicles is not determined, in an area where transportation is started, and the number of vehicles going out of the bay is large, shortage of vehicles occur, and wait time for transportation becomes extremely long.